Hey Razkanaz, sorry for the late reply:
1. it'll be emailed to you!
2. that was only for people who preordered last year unfortunately, before we took down this page publicly and removed the 'special thanks' perk from the list here. The people who preordered when the perk was still advertised should have received the email already last year confirming their credit name. We might decide to still include it as a thanks.txt somewhere in the game files for fun, but we will do an announcement here if we do